1. Field of the Invention (Technical Field):
The present invention relates to energy metering of conduits through which a fluid flows.
2. Background Art
Currently energy meters for liquid flow systems (e.g., solar systems) must be installed into the system to measure how much energy the system is producing or losing. This involves cutting pipes, installing thermal wells and flow meters, and/or connecting sensors to pump motors in the system. This often requires a licensed contractor or other authorized individual to complete the task. Many solar systems, for example, are too small and the value of the energy they collect is not sufficient to justify a commercially available BTU meter, which are relatively expensive.
The present invention is of an energy monitoring (metering) device that monitors energy from such systems using a simple technique that senses when the system is running and then estimates the BTU energy production. The metering system can be installed on a system without cutting any pipes or connecting to any electrical systems. The invention is, therefore, completely portable and can be installed without disturbing the system or engaging a contractor or other authorized personnel. The metering system of the invention is useful for both fixed and variable flow systems.
A device for measuring flows as opposed to energy is disclosed in S. M. Gleman, et al., “An Inexpensive Non-Invasive Flow Meter for Solar Applications,” Proceedings of the Annual Meeting of the American Section of the International Solar Energy Society, pp. 747–749 (1981). A technique to measure water flow in a pipe without invading the pipe is described wherein one puts so much heat into the pipe upstream and then measure the heat downstream. By knowing how much heat is put in, the size of the pipe (i.e., its mass), and the heat capacity of water, and the measured heat downstream, one can estimate the amount of water that is flowing.